DE 295 00 961 describes a vehicle antenna arrangement in which the antenna serves several functions including radio reception, mobile communications and the like. In such an antenna arrangement, means can be provided for the transmission and reception of radio frequency signals within an antenna housing or apart from the antenna housing, especially when the antenna is of the radio type. The housing can be affixed by an appropriate base to the roof of the vehicle and the roof of the vehicle can have an opening through which the electrical conductors servicing the antenna can extend. Below the housing, the electronic circuitry of the antenna can be provided, this circuitry serving to process the signals to and from the antenna.
Vehicles can also be provided with so-called keyless entry systems, generally in the form of a radio controlled central locking arrangement. That document, however, does not describe such a keyless entry system or any means which can facilitate the actuation of a keyless entry system by a radio-frequency signal from the exterior.
In practice, the transmission of a radiofrequency signal from, for example, a keyless entry transmitter external of the vehicle to a pickup within the interior of the vehicle has involved problems resulting from a shielding of the pickup within the vehicle interior caused by the body of the vehicle.
The pickup for such a keyless entry system has been a piece of coaxial cable which had a conductor extending from that cable with its free end located within the body of the vehicle and thereby shielding via the metallic part of the vehicle body. Sometimes that free conductor was located within a windshield or rear window of the vehicle and then shielding from a vapor-deposited metallic coating on the window could create problems.
As an alternative to cables of this type, functioning as antennae in the interior of the vehicle, were so-called window antennae, in which conductors in or on the window could receive signals for operating the keyless entry system. Such window antennae, however, were not available for some types of vehicles, for example convertibles, and were expensive for others.
Mention should be made as well of German utility model G 93 14 147.5 of Jan. 1994 which describes a vehicle antenna mounted on a vehicle body and serviced by a coaxial cable and to U.S. Pat. No. 6,339,403 which does have a remote keyless entry arrangement.